Introduction: Various improvements have been accomplished in order to provide a better solution for the restoration of missing teeth, but with limited success. Fixed bridges have been considered one of the most effective dental treatments for partially edentulous patients; however, a major disadvantage of fixed bridges is the aggressive reduction of the healthy natural abutment teeth. Another disadvantage of dental bridges is associated with the use of dental cements as they have issues regarding their relatively low strength and varying level of solubility. Accordingly, a new fixed bridge that is conservative for the abutment teeth and retained without using any cement was introduced in this study. Aims: The aim of this study is to produce a new fixed partial denture design with minimum abutment teeth reduction. The purpose of this in vitro study was to evaluate the maximum tensile force required to dislodge the conventional three-unit fixed partial denture, and to accordingly compare it with a new fixed bridge design. The obtained new bridge design should be fixed using mechanical force rather than chemical force. It has four clasps, each of which will be engaged into the prepared abutment teeth. Materials and Methods: Forty (40) extracted human teeth (20 second premolar, 20 second molars) were collected. A three-unit bridge case was then simulated by mounting one second premolar and one second molar in acrylic resin blocks, leaving the space of the first molar missing. Twenty (20) acrylic blocks were constructed and divided into two groups (n = 10). Teeth preparations were preformed according to each group criteria and with the objective to restore the missing first molar. Following, the prostheses were fabricated and casting was made in cobalt-chromium alloy. The metal frameworks on the first group (conventional three-unit FPDs) were cemented with zinc phosphate cement, and metal frameworks on the second group (new FPD designs) were fixed directly to the prepared teeth without the use of any cement. The specimens were then subjected to tensile loading at a cross-head speed of 0.5 mm/min in a universal testing machine. The mean separation forces in Newtons were recorded and statistically analysed with the application of a one-way analysis of variance (ANOVA). Results: The mean (SD) value of the maximum tensile force required for dislodging the conventional three-unit FPD frameworks were 170.97N (21.09) and for the new FPD framework were 387.80N (22.21). Conclusion: The conventional three-unit FPDs group showed a significantly lower mean dislodgment resistance compared with the new FPD designs group (P < 0.001). The current study indicates that the new suggested FPD can be clinically viable design in terms of mechanical retention, however, further clinical research need to be conducted.
|Date of Award||1 Aug 2012|
- The University of Manchester
|Supervisor||David Watts (Supervisor) & Kevin Seymour (Supervisor)|